M3 Headphone Amplifier - Take Two

This is a work in progress, this article is by no means complete yet!


Some time ago, a fellow head-fi'er put up a not-quite-finished M3 for sale and his add caught my attention. I had spoken with him in the past and seemed to remember that the M3 was a dream of his. It seemed he had done all the soldering, but that the casework had effectively stopped his project from being finalized. I contacted him and suggested that instead of selling the project (I already have an M3) we should build a proper case for it so that he would be able to enjoy music the way he intended to. He quickly accepted and we started talking design.

Hard decisions

This is what I got, along with a box of stuff for the build. The build featured: As you might gather, the original intention was to have a relay turn on the amp, we abandoned this idea. Also, he wanted to watch movies through this amp and I know from my Beta22
that the protection relay behaves quite erratic in the standard configuration and often triggers when I play PC games, so we abandoned that also. My own M3 does not have the protection relay either and I have never had a problem with it.


The Sigma11 was chosen as power supply as it complements the M3 design nicely.